Eyeless Fish in Indiana Caves (GM-10)
Two species of blind fish occur in Indiana caves: Ambylopsis spelaea, south of East Fork of White River, and Typhlichthys subterraneus, only near Corydon. Countless generations of these fish living in total darkness resulted in the loss of eyes, optic nerve, and skin pigmentations.

Blind fish are scavengers, feeding on organic matter washed into underground channels during rains. Although they lack natural predators, these fish produce no more offspring than the food supply will support.

The geologic setting in which organisms live directly affects their genetic development. The eyeless fish of southern Indiana are a dramatic example of adaptation to a world undergoing change by the geologic forces around us.

Our Hoosier State Beneath Us: Geomorphology